Diagnostic apparatus and power system including the same

ABSTRACT

Provided is a diagnostic apparatus for a power system. The power system comprises a battery assembly and at least one contactor. Each of the at least one contactor is configured to selectively close or open a power supply path between the battery assembly and a load. The diagnostic apparatus is configured to execute one of a first diagnostic function of determining a current leakage of the battery assembly and a second diagnostic function of determining a short circuit of the at least one contactor while the other one is being executed.

TECHNICAL FIELD

The present application claims priority to Korean Patent Application No.10-2016-0130781 filed on Oct. 10, 2016 in the Republic of Korea, thedisclosure of which is incorporated herein by reference.

The present disclosure relates to a diagnostic apparatus and a powersystem including the same, and more particularly, to an apparatus fordiagnosing a current leakage accident and a short circuit accidentgenerated in a power system, and the power system including theapparatus.

BACKGROUND ART

Recently, according to rapid increase in demands for portable electronicproducts, such as laptop computers, video cameras, portable phones, etc.and earnest development of electric cars, storage batteries for energystorage, robots, satellites, etc., studies of high performance secondarybatteries capable of repetitive charging and discharging are activelyconducted.

Currently commercialized secondary batteries are nickel cadmiumbatteries, nickel hydrogen batteries, nickel zinc batteries, lithiumsecondary batteries, etc. and the lithium secondary batteries thereamongare receiving attention according advantages of freecharging/discharging, a very low self-discharge rate, and high energydensity since a memory effect is barely generated compared tonickel-based secondary batteries.

Meanwhile, a power system is essential in various apparatuses thatrequire electric energy, such as electric cars. The power system is incharge of stable power supply between a battery and a load byselectively closing or opening at least one contactor.

In relation to safety of the power system, it is required to diagnosegeneration of largely two types of accidents. One is a current leakageaccident of a battery and the other one is a short circuit accident of acontactor. When the current leakage accident is generated, a user has arisk of getting an electric shock or the like, and when the shortcircuit accident is generated, there is a risk of sudden unintendedacceleration or the like.

A conventional art for diagnosing the current leakage accident and aconventional art for diagnosing a short circuit accident have been easydisclosed, but a conventional art for simultaneously diagnosing twotypes of accidents is not disclosed.

A critical safety problem may be generated if the current leakageaccident and the short circuit accident are not simultaneouslydiagnosed. For example, when a diagnosis of the short circuit accidentbegins after a diagnosis of the current leakage accident is completed,generation of the short circuit accident cannot be quickly notified to auser.

DISCLOSURE Technical Problem

The present disclosure is designed to solve the above problems, andtherefore the present disclosure is directed to providing a diagnosticapparatus capable of executing a second diagnostic function ofdetermining a short circuit of at least one contactor while a firstdiagnostic function of determining a current leakage of a battery moduleis being executed, or capable of executing the first diagnostic functionwhile the second diagnostic function is being executed, and a powersystem including the diagnostic apparatus.

These and other objects and advantages of the present disclosure may beunderstood from the following detailed description and will become morefully apparent from the exemplary embodiments of the present disclosure.Also, it will be easily understood that the objects and advantages ofthe present disclosure may be realized by the means shown in theappended claims and combinations thereof.

Technical Solution

Various embodiments of the present disclosure for achieving theobjectives are as follows.

In one aspect of the present disclosure, there is provided a diagnosticapparatus for a power system that includes a battery assembly, a firstcontactor, a second contactor, a first protection capacitor, and asecond protection capacitor. The diagnostic apparatus includes: a firstvoltage dividing unit connected between a ground of the power system anda first node to which a positive electrode of the battery assembly andone end of the first contactor are commonly connected, and configured togenerate a first detection voltage by dividing a voltage applied betweenthe first node and the ground; a second voltage dividing unit connectedbetween the ground and a second node to which a negative electrode ofthe battery assembly and one end of the second connector are commonlyconnected, and configured to generate a second detection voltage bydividing a voltage applied between the second node and the ground; athird voltage dividing unit connected between the second node and athird node to which one end of the first protection capacitor andanother end of the first contactor are commonly connected, andconfigured to generate a third detection voltage by dividing a voltagebetween the third node and the second node; and a control unitconfigured to control the first contactor, the second contactor, and thefirst through third voltage dividing units. The control unit may beconfigured to execute a first diagnostic function and a seconddiagnostic function during an inactive section where the first contactorand the second contactor are controlled in an opened state. The firstdiagnostic function may be a function of determining a current leakageof the battery assembly based on the first detection voltage and thesecond detection voltage, and the second diagnostic function may be afunction of determining a short circuit of at least one of the firstcontactor and the second contactor based on the third detection voltage.

The first voltage dividing unit may include: a first voltage dividerconfigured to divide a voltage applied between the first node and theground, and including a first protection resistor and a first detectionresistor; and a first switch configured to selectively apply the voltageapplied between the first node and the ground to the first voltagedivider, in response to a signal output from the control unit. Also, thesecond voltage dividing unit may include: a second voltage dividerconfigured to divide a voltage applied between the second node and theground, and including a second protection resistor and a seconddetection resistor; and a second switch configured to selectively applythe voltage applied between the second node and the ground to the secondvoltage divider, in response to a signal output from the control unit.In this case, the first detection resistor may generate the firstdetection voltage when the first switch is in a closed state, and thesecond detection resistor may generate the second detection voltage whenthe second switch is in a closed state.

The third dividing unit may include: a third voltage divider configuredto divide a voltage applied between the third node and the second node,and including a third protection resistor and a third detectionresistor; and a third switch configured to selectively apply the voltageapplied between the third node and the second node to the third voltagedivider, in response to a signal output from the control unit. In thiscase, the third detection resistor may generate the third detectionvoltage when the third switch is in a closed state.

Together or separately, the inactive section may include a firstswitching cycle in which the first switch and the third switch arecontrolled in a closed state, and the second switch is controlled in anopened state. The control unit may be configured to record a firstpattern including values of the third detection voltage measured aplurality of times according to time during the first switching cycle,and determine a short circuit of the first contactor based on the firstpattern.

Together or separately, the inactive section may include a secondswitching cycle in which the first switch is controlled in an openedstate, and the second switch and the third switch are controlled in aclosed state. The control unit may be configured to record a secondpattern comprising values of the third detection voltage measured aplurality of times according to time during the second switching cycle,and determine a short circuit of the second contactor based on thesecond pattern.

According to an embodiment, the inactive section may include: a firstswitching cycle in which the first switch and the third switch arecontrolled in a closed state, and the second switch is controlled in anopened state; and a second switching cycle in which the first switch iscontrolled in an opened state, and the second switch and the thirdswitch are controlled in a closed state. The control unit may beconfigured to determine that the first contactor and the secondcontactor are in a normal state when the third detection voltage isgradually decreased while having a positive value during the firstswitching cycle, and is gradually increased while having a negativevalue during the second switching cycle. Meanwhile, the control unit maybe configured to determine that the first contactor and the secondcontactor are short-circuited due to malfunction when a value of thethird detection voltage is maintained constant during the firstswitching cycle or the second switching cycle.

Together or separately, the control unit may include: a microprocessor;a multiplexer configured to select at least one of the first to thirddetection voltages, in response to a signal provided from themicroprocessor; and an analog-digital converter (ADC) configured toconvert a detection voltage selected by the multiplexer to a digitalsignal and transmit the digital signal to the microprocessor.

Preferably, another end of each of the first protection capacitor andthe second protection capacitor may be commonly connected to the ground.

In another aspect of the present disclosure, there is also provided apower system including the diagnostic apparatus.

In another aspect of the present disclosure, there is also provided anelectric car including the power system.

Advantageous Effects

According to at least one of embodiments of the present disclosure, asecond diagnostic function of determining a short circuit of at leastone contactor may be executed while a first diagnostic function ofdetermining a current leakage of a battery module is being executed, orthe first diagnostic function may be executed while the seconddiagnostic function is being executed. Accordingly, information aboutgeneration of a current leakage accident and a short circuit accidentmay be quickly notified to a user.

Effects of the present disclosure are not limited by the effectsdescribed above, and other effects that are not mentioned will becomeapparent to one of ordinary skill in the art from the appended claims.

DESCRIPTION OF DRAWINGS

The accompanying drawings illustrate a preferred embodiment of thepresent disclosure and together with the foregoing disclosure, serve toprovide further understanding of the technical features of the presentdisclosure, and thus, the present disclosure is not construed as beinglimited to the drawing.

FIGS. 1 and 2 are block diagrams schematically illustrating a functionalconfiguration of a power system and a diagnostic apparatus, according toan embodiment of the present disclosure.

FIG. 3 schematically illustrates a configuration of various circuitsthat may be included in the diagnostic apparatus of FIG. 2.

FIG. 4 schematically illustrates a configuration of various circuitsthat may be additionally included in the diagnostic apparatus of FIG. 2.

FIG. 5 is a block diagram schematically illustrating a functionalconfiguration of a control unit controlling an operation of a diagnosticapparatus.

FIGS. 6 and 7 are reference diagrams for explaining an operation of adiagnostic apparatus determining a current leakage of a battery module,according to an embodiment of the present disclosure.

FIGS. 8 and 9 are reference diagrams for explaining an operation of adiagnostic apparatus determining malfunction of at least one contact,according to an embodiment of the present disclosure.

FIGS. 10 and 11 illustrate circuits formable by a diagnostic apparatus,according to an embodiment of the present disclosure.

FIGS. 12 and 13 are graphs related to the circuits illustrated in FIGS.10 and 11.

BEST MODE

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail with reference to the accompanying drawings. Priorto the description, it should be understood that the terms used in thespecification and the appended claims should not be construed as limitedto general and dictionary meanings, but interpreted based on themeanings and concepts corresponding to technical aspects of the presentdisclosure on the basis of the principle that the inventor is allowed todefine terms appropriately for the best explanation.

Therefore, the description proposed herein is just a preferable examplefor the purpose of illustrations only, not intended to limit the scopeof the disclosure, so it should be understood that other equivalents andmodifications could be made thereto without departing from the scope ofthe disclosure.

Also, in the description of the present disclosure, detailedexplanations of related well-known configurations or functions may beomitted when it is deemed that they may obscure the essence of thedisclosure.

Throughout the specification, when a part “includes” a component, unlessthere is a particular description contrary thereto, the part can furtherinclude other components, not excluding the other components. In thefollowing description, terms such as <control unit> indicate a unit forprocessing at least one function or operation, wherein the control unitmay be embodied as hardware or software or embodied by combininghardware and software.

In addition, throughout the specification, when a region is “connected”to another region, the regions may not only be “directly connected”, butmay also be “indirectly connected” via another device therebetween.

FIGS. 1 and 2 are block diagrams schematically illustrating a functionalconfiguration of a power system 10 and a diagnostic apparatus 200,according to an embodiment of the present disclosure.

First, referring to FIG. 1, the power system 10 may be included in anapparatus capable of storing and supplying electric energy, such as anelectric car 1 or the like. Of course, the power system 10 may beincluded in a large-scale power storage system, such as an energystorage system, or in a small-scale power storage system, such as asmart phone, in addition to the electric car 1.

The power system 10 may basically include a battery module 100, thediagnostic apparatus 200, a noise removing circuit 300, and a load 400.

The battery module 100 includes at least one cell. When a plurality ofcells are included in the battery module 100, any one of them may beconnected to the other in series or in parallel. A cell included in thebattery module 100 may representatively be a lithium ion battery, alithium polymer battery, a nickel cadmium battery, a nickel hydrogenbattery, a nickel zinc battery, or the like. Of course, types of thecell are not limited to those listed above, and are not specificallylimited as long as the cell is repeatedly chargeable and dischargeable.

The load 400 converts electric energy provided from the battery module100 to another form of energy. For example, the load 400 may include anelectric motor, and in this case, the load 400 may convert electricenergy provided from the battery module 100 to rotation energy.Accordingly, a wheel and/or a cooling fan included in the electric car 1may be rotated. As another example, the load 400 may include a resistor.In this case, the load 400 may convert the electric energy provided fromthe battery module 100 to heat energy.

The noise removing circuit 300 is configured to remove noise transmittedfrom any one of the battery module 100 and the load 400 to the other oneby being connected between the battery module 100 and the load 400.

The diagnostic apparatus 200 is configured to diagnose generation of apre-determined type of accident by being connected between the batterymodule 100 and the load 400. The diagnostic apparatus 200 is configuredto determine at least a current leakage of the battery module 100. Inaddition, the diagnostic apparatus 200 may determine malfunction of atleast one contactor provided on a power supply path between the batterymodule 100 and the load 400. Furthermore, the diagnostic apparatus 200may control the power supply path between the battery module 100 and theload 400. Here, the at least one contactor may be provided in a form ofbeing included in the diagnostic apparatus 200.

FIG. 2 is a diagram illustrating, in detail, the power system 10 ofFIG. 1. Referring to FIG. 2, the battery module 100 includes a batteryassembly Batt including at least one cell. Also, the battery module 100may be represented in a form additionally including a first insulatingresistor Ra and a second insulating resistor Rb. The first insulatingresistor Ra and the second insulating resistor Rb may denote virtualresistors indicating insulating states respectively of a positiveelectrode and a negative electrode of the battery assembly Batt, insteadof physical resistors intentionally provided during manufacture of thebattery module 100.

When the power system 10 is included in the electric car 1, a ground 2may be chassis. The first insulating resistor Ra is provided in a formof being connected between the ground 2 and the positive electrode ofthe battery assembly Batt where a highest potential is formed. Thesecond insulating resistor Rb is provided in a form connected betweenthe ground 2 and the negative electrode of the battery assembly Battwhere a lowest potential is formed. The first insulating resistor Ra andthe second insulating resistor Rb are for preventing an electric shockaccident, and are capable of suppressing a leakage current flowing fromthe battery assembly Batt due to a current leakage only when arespectively resistance value is sufficiently high.

Electric energy stored in the battery assembly Batt is supplied to theload 400 connected to a first terminal P_(P) and a second terminalP_(N). The positive electrode of the battery assembly Batt iselectrically connected to the first terminal P_(P) through a first powerline L1. The negative electrode of the battery assembly Batt iselectrically connected to the second terminal P_(N) through a secondpower line L2.

Contactors SWC1 and SWC2 may be included in at least one of the firstpower line L1 and the second power line L2. For example, as illustrated,a first contactor SWC1 may be provided on the first power line L1, and asecond contactor SWC2 may be provided on the second power line L2. Inthis case, a power supply path through the first power line L1 may beselectively opened or closed by the first contactor SWC1, and a powersupply path through the second power line L2 may be selectively openedor closed by the second contactor SWC2. Power supply from the batteryassembly Batt to the load 400 is possible only when the first contactorSWC1 and the second contactor SWC2 are both in a closed state. In otherwords, power supply from the battery assembly Batt to the load 400 isblocked when at least one of the first contactor SWC1 and the secondcontactor SWC2 is in an opened state.

In some cases, any one of the first contactor SWC1 and the secondcontactor SWC2 may be omitted from the power system 10. For example,only the first contactor SWC1 from among the first contactor SWC1 andthe second contactor SWC2 may be embodied in a form of being included inthe power system 10. In this case, power supply between the batteryassembly Batt and the load 400 is blocked while the first contactor SWC1is in an opened state, and power supply between the battery assemblyBatt and the load 400 is performed only when the first contactor SWC1 isin a closed state. A contactor included in at least one of the firstpower line L1 and the second power line L2 may be included in thediagnostic apparatus 200 described later. Hereinafter, it is assumedthat the power system 10 includes both the first contactor SWC1 and thesecond contactor SWC2.

The noise removing circuit 300 may include a first protection capacitorC1 and a second protection capacitor C2. The first protection capacitorC1 and the second protection capacitor C2 is connected in series betweenthe first terminal P_(P) and the second terminal P_(N), and one of twoends of each is commonly connected to the ground 2. The first protectioncapacitor C1 and the second protection capacitor C2 may be referred toas a ‘Y-CAP’. The first protection capacitor C1 and the secondprotection capacitor C2 are configured to mitigate noise, such aselectromagnetic waves, transferred from any one of the battery assemblyBatt and the load 400 to the other, by respective capacitance.Hereinafter, it is assumed that the capacitance of the first protectioncapacitor Ca and the capacitance of the second protection capacitor C2are the same.

The diagnostic apparatus 200 may be configured to be selectivelyconnectable to at least one of a first node N1, a second node N2, athird node N3, a fourth node N4, and the ground 2.

The first node N1 is located between the positive electrode of thebattery assembly Batt and one end of the first contactor SWC1. In otherwords, the first node N1 is a node to which the positive electrode ofthe battery module 100 and the one end of the first contactor SWC1 arecommonly connected.

The second node N2 is located between the negative electrode of thebattery assembly Batt and one end of the second contactor SWC2. In otherwords, the second node N2 is a node to which the negative electrode ofthe battery module 100 and the one end of the second contactor SWC2 arecommonly connected.

The third node N3 is located between one of two ends of the firstprotection capacitor C1, which is not connected to the ground 2, and theother end of the first contactor SWC1. In other words, the third node N3is a node to which the one end of the first protection capacitor C1 andthe other end of the first contactor SWC1 are commonly connected.

The fourth node N4 is located between one of two ends of the secondprotection capacitor C2, which is not connected to the ground 2, and theother end of the second contactor SWC2. In other words, the fourth nodeN4 is a node to which the one end of the second protection capacitor C2and the other end of the second contactor SWC2 are commonly connected.

The diagnostic apparatus 200 may select two points that are combinablefrom the first node N1, the second node N2, the third node N3, thefourth node N4, and the ground 2, and measure a voltage applied betweenthe selected two points. For example, the diagnostic apparatus 200 maymeasure a voltage between the first node N1 and the fourth node N4. Asanother example, the diagnostic apparatus 200 may measure a voltagebetween the first node N1 and the ground 2.

The diagnostic apparatus 200 may sequentially or simultaneouslydetermine a current leakage of the battery module 100 and malfunction ofthe contactors SWC1 and SWC2 based on a voltage related to at least oneof the first node N1, the second node N2, the third node N3, and thefourth node N4. This will be described in detail below with reference toFIGS. 3 through 13.

FIG. 3 schematically illustrates a configuration of various circuitsthat may be included in the diagnostic apparatus 200 of FIG. 2.

Referring to FIG. 3, the diagnostic apparatus 200 may include aplurality of voltage dividing units 210, 220, 230, and 240.

A first voltage dividing unit 210 is provided to be connectable betweenthe first node N1 and the ground 2. The first voltage dividing unit 210is configured to generate a first detection voltage V1 corresponding toa voltage applied between the first node N1 and the ground 2. In detail,the first voltage dividing unit 210 may include a first switch SW1 and afirst voltage divider that are configured to be connected to each otherin series. The first voltage divider may include a first protectionresistor R11 and a first detection resistor R12. The first switch SW1 isconfigured to selectively apply a voltage applied between the positiveelectrode and the ground 2 to the first voltage divider, in response toa signal output from a control unit 270 described later. The voltageapplied between the first node N1 and the ground 2 is divided by thefirst voltage divider when the first switch SW1 is in a closed state.The first detection voltage V1 denotes a voltage applied to two ends ofthe first detection resistor R12. In FIG. 3, the first switch SW1 isconnected between the first protection resistor R11 and the firstdetection resistor R12, but a connection order therebetween is notlimited.

A second voltage dividing unit 220 is provided to be connectable betweenthe second node N2 and the ground 2. The second voltage dividing unit220 is configured to generate a second detection voltage V2corresponding to a voltage applied between the second node N2 and theground 2. In detail, the second voltage dividing unit 220 may include asecond switch SW2 and a second voltage divider that are configured to beconnected to each other in series. The second voltage divider mayinclude a second protection resistor R21 and a second detection resistorR22. The second switch SW2 is configured to selectively apply a voltageapplied between the negative electrode and the ground 2 to the secondvoltage divider, in response to a signal output from the control unit270 described later. The voltage applied between the second node N2 andthe ground 2 is divided by the second voltage divider when the secondswitch SW2 is in a closed state. The second detection voltage V2 denotesa voltage applied to two ends of the second detection resistor R22. InFIG. 3, the second switch SW2 is connected between the second protectionresistor R21 and the second detection resistor R22, but a connectionorder therebetween is not limited.

A ratio between a resistance value of the first protection resistor R11and a resistance value of the first detection resistor R12 may bedesigned to be equal to a ratio between the resistance value of thesecond protection resistor R21 and a resistance value of the seconddetection resistor R22. For example, the resistance value of the firstprotection resistor R11 and the resistance value of the secondprotection resistor R21 may be the same, and the resistance value of thefirst detection resistor R12 and the resistance value of the seconddetection resistor R22 may be the same. Here, in order to protect thefirst detection resistor R12 and the second detection resistor R22 froma high voltage, the resistance value of each of the first protectionresistor R11 and the second protection resistor R21 may be designed tobe sufficiently larger than the resistance value of each of the firstdetection resistor R12 and the second detection resistor R22. Forexample, the resistance value of the first protection resistor R11 maybe 99 times larger than the resistance value of the first detectionresistor R12, and at this time, the first detection voltage V1corresponds to 1/100 of the voltage applied between the first node N1and the ground 2.

The first voltage dividing unit 210 and the second voltage dividing unit220 may be used to determine a current leakage of the battery module100.

The control unit 270 may calculate a voltage VB between the positiveelectrode and the negative electrode of the battery assembly Batt basedon the first detection voltage V1 and the second detection voltage V2.

A third voltage dividing unit 230 is provided to be connectable betweenthe third node N3 and the second node N2. The third voltage dividingunit 230 is configured to generate a third detection voltage V3corresponding to a voltage applied between the third node N3 and thesecond node N2. In detail, the third voltage dividing unit 230 mayinclude a third switch SW3 and a third voltage divider. The thirdvoltage divider may include a third protection resistor R31 and a thirddetection resistor R32. The third switch SW3 is configured toselectively apply a voltage applied between the third node N3 and thesecond node N2 to the third voltage divider, in response to a signaloutput from the control unit 270 described later. The voltage appliedbetween the third node N3 and the second node N2 is divided by the thirdvoltage divider when the third switch SW3 is in a closed state. Thethird detection voltage V3 denotes a voltage applied to two ends of thethird detection resistor R32. In FIG. 3, the third switch SW3 isconnected between the third protection resistor R31 and the thirddetection resistor R32, but a connection order therebetween is notlimited.

A fourth voltage dividing unit 240 is provided to be connectable betweenthe first node N1 and the second node N2. The fourth voltage dividingunit 240 is configured to generate a fourth detection voltage V4corresponding to a voltage applied between the first node N1 and thesecond node N2, i.e., the voltage VB of the battery assembly Batt.

In detail, the fourth voltage dividing unit 240 may include a firstswitch SW4 and a fourth voltage divider. The fourth voltage divider mayinclude a fourth protection resistor R41 and a fourth detection resistorR42. The fourth switch SW4 is configured to selectively apply thevoltage applied between the first node N1 and the second node N2 to thefourth voltage divider, in response to a signal output from the controlunit 270 described later. The voltage applied between the first node N1and the second node N2 is divided by the fourth voltage divider when thefourth switch SW4 is in a closed state. The fourth detection voltage V4denotes a voltage applied to two ends of the fourth detection resistorR42. In FIG. 3, the fourth switch SW4 is connected between the fourthprotection resistor R41 and the fourth detection resistor R42, but aconnection order therebetween is not limited.

The control unit 270 may calculate the voltage VB of the batteryassembly Batt based on the fourth detection voltage V4.

A ratio between a resistance value of the fourth protection resistor R41and a resistance value of the fourth detection resistor R42 may bedesigned to be equal to a ratio between a resistance value of the thirdprotection resistor R31 and a resistance value of the third detectionresistor R32. For example, the resistance value of the fourth protectionresistor R41 and the resistance value of the third protection resistorR31 may be the same, and the resistance value of the fourth detectionresistor R42 and the resistance value of the third detection resistorR32 may be the same. Here, in order to protect the fourth detectionresistor R42 and the third detection resistor R32 from a high voltage,the resistance value of each of the fourth protection resistor R41 andthe third protection resistor R31 may be designed to be sufficientlylarger than the resistance value of each of the fourth detectionresistor R42 and the third detection resistor R32.

The third voltage dividing unit 230 may be used to diagnose malfunctionof the first contactor SWC1 and/or the second contactor SWC2. The fourthvoltage dividing unit 240 may be used to diagnose a current leakage ofthe battery module 100 and malfunction of the first contactor SWC1and/or the second contactor SWC2.

FIG. 4 schematically illustrates a configuration of various circuitsthat may be additionally included in the diagnostic apparatus 200 ofFIG. 2.

Referring to FIG. 4, the diagnostic apparatus 200 may further include atleast one of a fifth voltage dividing unit 250 and a sixth voltagedividing unit 260.

The fifth voltage dividing unit 250 may be provided to be connectablebetween the first node N1 and the fourth node N4. The fifth voltagedividing unit 250 is configured to generate a fifth detection voltage V5corresponding to a voltage applied between the first node N1 and thefourth node N4. In detail, the fifth voltage dividing unit 250 mayinclude a fifth switch SW5 and a fifth voltage divider. The fifthvoltage divider may include a fifth protection resistor R51 and a fifthdetection resistor R52. The fifth switch SW5 is configured toselectively apply a voltage applied between the first node N1 and thefourth node N4 to the fifth voltage divider, in response to a signaloutput from the control unit 270 described later. The voltage appliedbetween the first node N1 and the fourth node N4 is divided by the fifthvoltage divider when the fifth switch SW5 is in a closed state. Thefifth detection voltage V5 denotes a voltage applied to two ends of thefifth detection resistor R52. In FIG. 3, the fifth switch SW5 isconnected between the fifth protection resistor R51 and the fifthdetection resistor R52, but a connection order therebetween is notlimited.

The sixth voltage dividing unit 260 may be provided to be connectablebetween the third node N3 and the fourth node N4. The sixth voltagedividing unit 260 is configured to generate a sixth detection voltage V6corresponding to a voltage applied between the third node N3 and thefourth node N4. In detail, the sixth voltage dividing unit 260 mayinclude a sixth switch SW6 and a sixth voltage divider. The sixthvoltage divider may include a sixth protection resistor R61 and a sixthdetection resistor R62. The sixth switch SW6 is configured toselectively apply the voltage applied between the third node N3 and thefourth node N4 to the sixth voltage divider, in response to a signaloutput from the control unit 270 described later. The voltage appliedbetween the third node N3 and the fourth node N4 is divided by the sixthvoltage divider when the sixth switch SW6 is in a closed state. Thesixth detection voltage V6 denotes a voltage applied to two ends of thesixth detection resistor R62. In FIG. 3, the sixth switch SW6 isconnected between the sixth protection resistor R61 and the sixthdetection resistor R62, but a connection order therebetween is notlimited.

A ratio between a resistance value of the fifth protection resistor R51and a resistance value of the fifth detection resistor R52 may bedesigned to be equal to a ratio between a resistance value of the sixthprotection resistor R61 and a resistance value of the sixth detectionresistor R62. For example, the resistance value of the fifth protectionresistor R51 and the resistance value of the sixth protection resistorR61 may be the same, and the resistance value of the fifth detectionresistor R52 and the resistance value of the sixth detection resistorR62 may be the same. Here, in order to protect the fifth detectionresistor R52 and the sixth detection resistor R62 from a high voltage,the resistance value of each of the fifth protection resistor R51 andthe sixth protection resistor R61 may be designed to be sufficientlylarger than the resistance value of each of the fifth detection resistorR52 and the sixth detection resistor R62.

The fifth voltage dividing unit 250 may be used to determine malfunctionof the second contactor SWC2. The sixth voltage dividing unit 260 may beused to determine malfunction of the first contactor SWC1 and the secondcontactor SWC2.

In relation to FIGS. 3 and 4, the diagnostic apparatus 200 may basicallyinclude the first voltage dividing unit 210, the second voltage dividingunit 220, the third voltage dividing unit 230, and the control unit 270,and may further include at least one of the fourth voltage dividing unit240, the fifth voltage dividing unit 250, and the sixth voltage dividingunit 260 according to an embodiment.

Hereinafter, it is assumed that resistance values of the first throughsixth switches SW1 through SW6, the contactors SWC1 and SWC2, and thepower lines L1 and L2 are so small as to be negligible.

FIG. 5 is a block diagram schematically illustrating a functionalconfiguration of the control unit 270 controlling an operation of thediagnostic apparatus 200.

Referring to FIG. 5, the control unit 270 of the diagnostic apparatus200 may include a microprocessor 271, a multiplexer 272, and an ADC 273.The ADC 273 denotes an analog-digital converter.

The microprocessor 271 may manage overall operations of the diagnosticapparatus 200. The microprocessor 271 is communicably connected to othercomponents included in the diagnostic apparatus 200 so as to transmit orreceive a signal related to the power system 10.

The microprocessor 271 may output signals of designating operationstates of the plurality of switches SW1 through SW6 and at least one ofthe contactors SWC1 and SWC2. In other words, the microprocessor 271 mayindividually control the plurality of switches SW1 through SW6 and atleast one of the contactors SWC1 and SWC2 so as to induce each of themto be in an opened state or a closed state. The microprocessor 271 mayoutput a signal S commanding selecting of at least one of the firstthrough sixth detection voltages V1 through V6 according to apre-determined rule.

At least one memory may be embedded in the microprocessor 271. Thememory may pre-store a program and data related to various operationsperformed by the diagnostic apparatus 200. For example, the memory maystore resistance values of resistors included in each of the firstthrough sixth voltage dividing units 210 through 260. As anotherexample, the memory may have recorded thereon data and software formeasuring detection voltages and determining generation of several typesof accidents based on measured results.

The multiplexer 272 includes a plurality of voltage input ports I1through I6, a selection input port IS, and an output port OUT. Thedetection voltages V1 through V6 generated by voltage generation unitsmay be respectively applied to the voltage input ports I1 through I6.

The signal S output from the microprocessor 271 is input to theselection input port IS. The multiplexer 272 selects any one of theplurality of voltage input ports I1 through I6 based on the signal inputto the selection input port IS, and connects the selected voltage inputport to the output port OUT. In other words, the multiplexer 272 isconfigured to selectively output one of the detection voltages V1through V6.

The ADC 273 converts an analog signal A provided from the multiplexer272 to a digital signal D, and transfers the digital signal D to themicroprocessor 271. It is obvious to one of ordinary skill in the artthat the analog signal A may be any one of the detection voltages V1through V6. The microprocessor 271 may individually measure thedetection voltages V1 through V6 based on the digital signal D receivedfrom the ADC 273. For example, the microprocessor 271 may measure thedetection voltage V1 based on the digital signal D transmitted from theADC 273, while the voltage input port I1 and the output port OUT areconnected by the multiplexer 272 according to a command of themicroprocessor 271.

The microprocessor 271 may determine each of a current leakage of thebattery module 100 and/or malfunction of at least one contactor based onmeasurement results with respect to the detection voltages V1 throughV6, and output alarm signals W1 and W2 each notifying a determinationresult.

FIGS. 6 and 7 are diagrams referred to so as to describe an operation ofthe diagnostic apparatus 200 determining a current leakage of thebattery module 100, according to an embodiment of the presentdisclosure. For convenience of description, it is assumed that thevoltage VB of the battery assembly Batt is pre-measured.

FIG. 6 illustrates a first circuit 600 formed in the power system 10.Referring to FIGS. 2 and 3 together, the control unit 270 may form thefirst circuit 600 by controlling the first switch SW1 to be in a closedstate and at least the second switch SW2 from among the remainingswitches SW2 through SW6 and the contactors SWC1 and SWC2 to be in anopened state. The control unit 270 may measure the first detectionvoltage V1 provided from the first voltage dividing unit 210 while thefirst circuit 600 is formed.

When the positive electrode of the battery assembly Batt is leaking, aresistance value of the first insulating resistor Ra becomes very smallcompared to when it does not leak. Accordingly, since most of thevoltage VB of the battery assembly Batt is applied to the secondinsulating resistor Rb, a magnitude of the first detection voltage V1measured during current leakage may be smaller than a value measuredduring non-current leakage.

FIG. 7 illustrates a second circuit 700 formed in the power system 10.Referring to FIGS. 2 and 3 together, the control unit 270 may form thesecond circuit 700 by controlling the second switch SW2 to be in aclosed state and at least the first switch SW1 from among the remainingswitches SW1 and SW3 through SW6 and the contactors SWC1 and SWC2 to bein an opened state. The control unit 270 may measure the seconddetection voltage V2 provided from the second voltage dividing unit 220while the second circuit 700 is formed.

When the negative electrode of the battery assembly Batt is leaking, aresistance value of the second insulating resistor Rb becomes very smallcompared to when it does not leak. Accordingly, since most of thevoltage VB of the battery assembly Batt is applied to the firstinsulating resistor Ra during current leakage of the negative electrodeof the battery assembly Batt, a magnitude of the second detectionvoltage V2 measured during the current leakage may be smaller than avalue measured during non-current leakage.

FIGS. 8 and 9 are diagrams referred to so as to describe an operation ofa diagnostic apparatus determining malfunction of at least one contact,according to an embodiment of the present disclosure. For convenience ofdescription, illustration of the first insulating resistor Ra and thesecond insulating resistor Rb are omitted, and it is assumed that thevoltage VB of the battery assembly Batt is pre-measured.

FIG. 8 illustrates a third circuit 800 formed in the power system 10 fordetermining a disconnection (open circuit fault) caused by malfunctionof the first contactor SWC1. Referring to FIGS. 2 and 3 together, thecontrol unit 270 may form the third circuit 800 by controlling the thirdswitch SW3 and the first contactor SWC1 to be in a closed state, andcontrolling at least the first switch SW1, the second switch SW2, andthe second contactor SWC2 from among the remaining switches and thesecond contactor SWC2 to be in an opened state. In the third circuit800, since the first switch SW1, the second switch SW2, and the secondcontactor SWC2 are in an opened state, the first protection capacitor C1and the second protection capacitor C2 may not affect the voltageapplied between the third node N3 and the second node N2. The controlunit 270 may measure the third detection voltage V3 provided from thethird voltage dividing unit 230 while the third circuit 800 is formed.

The control unit 270 may determine a disconnection of the firstcontactor SWC1 by comparing the voltage VB of the battery assembly Batt,which is pre-measured, and the third detection voltage V3 measured fromthe third circuit 800. For example, it may be determined thatdisconnection malfunction of the first contactor SWC1 is generated whenthe third detection voltage V3 is lower than the voltage VB of thebattery assembly Batt by at least a pre-determined first set value.

FIG. 9 illustrates a fourth circuit 900 formed in the power system 10for determining a short circuit (short circuit fault) caused bymalfunction of the first contactor SWC1. A short-circuited state causedby malfunction may be referred to as a ‘stuck closed status’.

Referring to FIGS. 2 and 3 together, the control unit 270 may form thefourth circuit 900 by controlling the third switch SW3 to be in a closedstate, and controlling at least the first switch SW1 and the secondswitch SW2 from among the remaining switches, and the first contactorSWC1 and the second contactor SWC2 to be in an opened state. In thefourth circuit 900, since the first switch SW1, the second switch SW2,and the second contactor SWC2 are in an opened state, the firstprotection capacitor C1 and the second protection capacitor C2 may notaffect the voltage applied between the third node N3 and the second nodeN2. The control unit 270 may measure the third detection voltage V3provided from the third voltage dividing unit 230 while the fourthcircuit 900 is formed.

The control unit 270 may determine a short circuit of the firstcontactor SWC1 by comparing the voltage VB of the battery assembly Batt,which is pre-measured, and the third detection voltage V3 measured fromthe fourth circuit 900. For example, it may be determined that the firstcontactor SWC1 is short-circuited when the third detection voltage V3 islower than the voltage VB of the battery assembly Batt by apre-determined second set value.

In FIGS. 8 and 9, the circuits 800 and 900 for determining malfunctionof the first contactor SWC1 have been mainly described, but malfunctionof the second contactor SWC2 may be determined in the similar manner byusing the fifth voltage dividing unit 250 instead of the third voltagedividing unit 230. In detail, the control unit 270 may determine that adisconnection malfunction of the second contactor SWC2 is generated whenthe fifth detection voltage V5 measured, in order to determinedisconnection of the second contactor SWC2, while the fifth switch SW5and the second contactor SWC2 are in a closed state and at least thefirst switch SW1, the second switch SW2, and the first contactor SWC1from among the remaining switches and the second contactor SWC2 are inan opened state is lower than the voltage VB of the battery assemblyBatt by at least a third pre-determined third set value.

Alternatively, it may be determined that a short circuit of the secondcontactor SWC2 is generated when the fifth detection voltage V5measured, in order to determine the short circuit of the secondcontactor SWC2, while the fifth switch SW5 is in a closed state and atleast the first switch SW1 and the second switch SW2 from among theremaining switches, and the first contactor SWC1 and the second switchSW2 are in an opened state is lower than the voltage VB of the batteryassembly Batt by a fourth pre-determined third set value.

FIGS. 10 and 11 illustrate circuits formable by the diagnostic apparatus200, according to an embodiment of the present disclosure, and FIGS. 12and 13 are graphs related to the circuits illustrated in FIGS. 10 and11. For convenience of description, illustration of the first insulatingresistor Ra and the second insulating resistor Rb are omitted, and it isassumed that the voltage VB of the battery assembly Batt ispre-measured.

Referring to FIG. 10 together with FIGS. 2 and 3, a fifth circuit 1000formed in the power system 10 is identified. The fifth circuit 1000 is acircuit formed while the first switch SW1 and the third switch SW3 arein a closed state, and the second switch SW2, the first contactor SWC1,and the second contactor SWC2 are in an opened state. The fifth circuit1000 is a closed circuit including a positive electrode, the first nodeN1, the first voltage dividing unit 210, the ground 2, the firstprotection capacitor C1, the third node N3, and the third voltagedividing unit 230. Hereinafter, a section where the fifth circuit 1000is continuously maintained is referred to as a ‘first switching cycle’.

As illustrated, when the fifth circuit 1000 is formed, the firstprotection capacitor C1 is charged as the current I1 flows in adirection from the positive electrode to the negative electrode of thebattery assembly Batt, by the voltage VB of the battery assembly Batt.As the first protection capacitor C1 is gradually charged, the thirddetection voltage V3 is gradually reduced by having a positive value.For example, when the fifth circuit 1000 is maintained for a long periodof time, a voltage of the first protection capacitor C1 will become thesame as the voltage VB of the battery assembly Batt, and as a result,the third detection voltage V3 will become 0 V.

Referring to FIG. 11 together with FIGS. 2 and 3, a sixth circuit 1100formed in the power system 10 is identified. The sixth circuit 1100 is acircuit formed while the second switch SW2 and the third switch SW3 arein a closed state, and the first switch SW1, the first contactor SWC1,and the second contactor SWC2 are in an opened state. The sixth circuit1100 is a closed circuit including the second node N2, the secondvoltage dividing unit 220, the ground 2, the first protection capacitorC1, the third node N3, and the third voltage dividing unit 230.Hereinafter, a section where the sixth circuit 1100 is continuouslymaintained is referred to as a ‘second switching cycle’.

As illustrated, when the sixth circuit 1100 is formed, the firstprotection capacitor C1 is discharged and a voltage of an inversedirection is applied to the third detection resistor R32 according toflow of the current I2. In other words, the third detection voltage V3detected by the control unit 270 has a negative value. In this case, asthe first protection capacitor C1 is gradually discharged, the thirddetection voltage V3 is increased towards 0 V.

Lengths of the first switching cycle and the second switching cycledescribed above may be set to be the same. Together or individually, thecontrol unit 270 may alternately execute the first switching cycle andthe second switching cycle while controlling the first contactor SWC1and the second contactor SWC2 to be both in an opened state. Forexample, the first switching cycle and the second switching cycle may beexecuted in an order of first switching cycle→second switchingcycle→first switching cycle→second switching cycle.

As will be described below, the fifth circuit 1000 may be formed whilethe first circuit 600 is formed. In other words, a period where thefirst circuit 600 is formed and a period where the fifth circuit 1000 isformed may at least partially overlap. Also, the sixth circuit 1100 maybe formed while the second circuit 700 is formed. In other words, aperiod where the second circuit 700 is formed and a period where thesixth circuit 1100 is formed may at least partially overlap. In thisregard, it is possible to determine a short circuit of the firstcontactor SWC1 and the second contactor SWC2 by using the fifth circuit1000 and the sixth circuit 1100 while determining a current leakage ofthe battery module 100 by using the first circuit 600 and the secondcircuit 700.

Hereinafter, a section where the control unit 270 controls the firstcontactor SWC1 and the second contactor SWC2 to be both in an openedstate is referred to as an ‘inactive section’ and a section where thecontrol unit 270 controls the first contactor SWC1 and the secondcontactor SWC2 to be both in a closed state is referred to as an ‘activesection’, and it is assumed that the voltage VB of the battery assemblyBatt is maintained constant. In this regard, the first switching cycleand the second switching cycle described above both belong to theinactive section. Also, it is obvious to one of ordinary skill in theart that power supply between the battery module 100 and the load 400 ispossible during the active section, and power supply between the batterymodule 100 and the load 400 is blocked during the inactive section.

In FIGS. 12 and 13, before T0 and after T2 belong to an active section,and from T0 to T2 belong to an inactive section. In the inactive sectionof FIGS. 12 and 13, it is assumed that the first switching cycle and thesecond switching cycle are each executed once for periods of time, whichdo not overlap each other. Of course, at least one of the firstswitching cycle and the second switching cycle may be executed at leasttwice during the inactive section.

First, FIG. 12 illustrates a pattern indicating a change of the thirddetection voltage V3 according to time, when the first contactor SWC1and the second contactor SWC2 are in a normal state without a shortcircuit caused by malfunction. In detail, before T0 and after T2, sincethe voltage VB of the battery assembly Batt is applied between the thirdnode N3 and the second node N2 through the first contactor SWC1 and thesecond contactor SWC2, the third detection voltage V3 may be maintainedto a uniform positive value VS.

The control unit 270 may record a first pattern including valuesobtained by measuring the third detection voltage V3 a plurality oftimes according to time, during the first switching cycle from T0 to T1where the fifth circuit 1000 of FIG. 10 is formed.

The control unit 270 may record a second pattern including valuesobtained by measuring the third detection voltage V3 a plurality oftimes according to time, during the second switching cycle from T1 to T2where the sixth circuit 1100 of FIG. 11 is formed. Here, the secondpattern may be recorded separately from the first pattern.

As shown in FIG. 12, the first pattern may be a pattern that isgradually decreased while having a positive value (i.e., higher than 0V), and the second pattern may be a pattern that is gradually increasedwhile having a negative value (i.e., lower than 0 V).

The control unit 270 may determine that the first contactor SWC1 is in anormal state when the first pattern recorded during the first switchingcycle has a form shown in FIG. 12.

The control unit 270 may determine that the second contactor SWC2 is ina normal state when the pattern recorded during the second switchingcycle has a form shown in FIG. 12.

When the first pattern recorded during the first switching cycle and thesecond pattern recorded during the second switching cycle both have theforms shown in FIG. 12, the control unit 270 may determine both thefirst contactor SWC1 and the second contactor SWC2 are in a normalstate.

Meanwhile, when only the first contactor SWC1 from among the firstcontactor SWC1 and the second contactor SWC2 is short-circuited due tomalfunction, the first node N1 and the third node N3 are electricallyconnected through the first contactor SWC1 despite the inactive sectiondesignated by the control unit 270. In this case, since the voltage VBof the battery assembly Batt is applied to the third voltage dividingunit 230, the third detection voltage V3 may not follow the firstpattern as shown in FIG. 12.

Also, when only the second contactor SWC2 from among the first contactorSWC1 and the second contactor SWC2 is short-circuited due tomalfunction, the second node N2 and the fourth node N4 are electricallyconnected through the second contactor SWC2 despite the inactive sectiondesignated by the control unit 270. In this case, the second voltagedividing unit 220 and the second protection capacitor C2 are connectedin parallel, and the third detection voltage V3 does not follow thesecond pattern as shown in FIG. 12. For example, the third detectionvoltage V3 may be equal to or higher than 0 V.

Next, FIG. 13 illustrates a pattern indicating a change of the thirddetection voltage V3 according to time, when the first contactor SWC1and the second contactor SWC2 are both short-circuited due tomalfunction. As shown in FIG. 12, since the voltage VB of the batteryassembly Batt is applied between the third node N3 and the second nodeN2 through the first contactor SWC1 and the second contactor SWC2 beforeT0 and after T2, the third detection voltage V3 may be maintainedconstant to the positive value VS.

However, when the first contactor SWC1 and the second contactor SWC2 areboth short-circuited, the first contactor SWC1 and the second contactorSWC2 both maintain a closed state despite the inactive sectiondesignated by the control unit 270. Accordingly, as shown in FIG. 13,the third detection voltage V3 may maintain the uniform value VS from T0to T2 where the first switching cycle and the second switching cycle arealternately executed, which is a clear contrast to a continuous changingpattern of the third detection voltage V3 shown in FIG. 12.

Referring to FIGS. 10 and 12, if the first contactor SWC1 and the secondcontactor SWC2 are not short-circuited, it is determined that the thirddetection voltage V3 changes according to time while the first switchingcycle or the second switching cycle is executed. Accordingly, it isdifficult to specify the value of third detection voltage V3 comparedwith the voltage VB of the battery assembly Batt, which hispre-measured, during the first switching cycle or the second switchingcycle. Accordingly, during the first switching cycle or the secondswitching cycle, it is possible to record a pattern including valuesobtained by measuring the third detection voltage V3 changing accordingto time a plurality of times, and simultaneously or sequentiallydetermine short circuits of the first contactor SWC1 and the secondcontactor SWC2 based on the recorded pattern.

As a result, the first diagnostic function of determining a currentleakage of the battery module 100, and the second diagnostic function ofdetermining a short circuit of at least one of the contactors SWC1 andSWC2 may not have to be executed at different periods of time, which donot overlap each other. In other words, the second diagnostic functionmay be executed while the first diagnostic function is executed, and thefirst diagnostic function may be executed while the second diagnosticfunction is executed.

Of course, as occasion demands, periods of time when the firstdiagnostic function and the second diagnostic function are performed maybe controlled by the control unit 270 to not to overlap each other.

Referring back to FIG. 5, the control unit 270 may output a first alarmsignal W1 notifying an execution result of the first diagnostic functionand/or a second alarm signal SW notifying an execution result of thesecond diagnostic function.

The first alarm signal W1 and the second alarm signal W2 output from thecontrol unit 270 may be converted to a form recognizable by a userthrough an information guide device (not shown) included in the powersystem 10 and/or the electric car 1. For example, the information guidedevice may convert and output the alarm signals W1 and S2 to a visualand/or acoustic signal.

Embodiments of the present disclosure described above are not embodiedonly through an apparatus and a method, but may be embodied through aprogram realizing a function corresponding to a feature of theembodiments of the present disclosure or a recording medium havingrecorded thereon the program, and such embodiments may be easilyembodied by one of ordinary skill in the art from the description of theembodiments described above.

The present disclosure has been described by limited embodiments anddrawings, but the present disclosure is not limited thereto, and variouschanges and modifications are possible within the scope of thedisclosure and the equivalent range of appended claims by one ofordinary skill in the art.

Also, since the present disclosure described above may be variouslysubstituted, modified, and changed by one of ordinary skill in the artwithin the range of the technical ideas of the present disclosure, thepresent disclosure is not limited by the above-described embodiments andappended drawings, but all or some of the embodiments may be selectivelycombined for various modifications.

1. A diagnostic apparatus for a power system that comprises a batteryassembly, a first contactor, a second contactor, a first protectioncapacitor, and a second protection capacitor, the diagnostic apparatuscomprising: a first voltage dividing unit connected between a ground ofthe power system and a first node to which a positive electrode of thebattery assembly and one end of the first contactor are commonlyconnected, and configured to generate a first detection voltage bydividing a voltage applied between the first node and the ground; asecond voltage dividing unit connected between the ground and a secondnode to which a negative electrode of the battery assembly and one endof the second connector are commonly connected, and configured togenerate a second detection voltage by dividing a voltage appliedbetween the second node and the ground; a third voltage dividing unitconnected between the second node and a third node to which one end ofthe first protection capacitor and another end of the first contactorare commonly connected, and configured to generate a third detectionvoltage by dividing a voltage between the third node and the secondnode; and a control unit configured to control the first contactor, thesecond contactor, and the first through third voltage dividing units,wherein the control unit is configured to execute a first diagnosticfunction and a second diagnostic function during an inactive sectionwhere the first contactor and the second contactor are controlled in anopened state, wherein the first diagnostic function is a function ofdetermining a current leakage of the battery assembly based on the firstdetection voltage and the second detection voltage, and the seconddiagnostic function is a function of determining a short circuit of atleast one of the first contactor and the second contactor based on thethird detection voltage.
 2. The diagnostic apparatus of claim 1, whereinthe first voltage dividing unit comprises: a first voltage dividerconfigured to divide a voltage applied between the first node and theground, and comprising a first protection resistor and a first detectionresistor; and a first switch configured to selectively apply the voltageapplied between the first node and the ground to the first voltagedivider, in response to a signal output from the control unit, and thesecond voltage dividing unit comprises: a second voltage dividerconfigured to divide a voltage applied between the second node and theground, and comprising a second protection resistor and a seconddetection resistor; and a second switch configured to selectively applythe voltage applied between the second node and the ground to the secondvoltage divider, in response to a signal output from the control unit,wherein the first detection resistor generates the first detectionvoltage when the first switch is in a closed state, and the seconddetection resistor generates the second detection voltage when thesecond switch is in a closed state.
 3. The diagnostic apparatus of claim2, wherein the third dividing unit comprises: a third voltage dividerconfigured to divide a voltage applied between the third node and thesecond node, and comprising a third protection resistor and a thirddetection resistor; and a third switch configured to selectively applythe voltage applied between the third node and the second node to thethird voltage divider, in response to a signal output from the controlunit, wherein the third detection resistor generates the third detectionvoltage when the third switch is in a closed state.
 4. The diagnosticapparatus of claim 3, wherein the inactive section comprises a firstswitching cycle in which the first switch and the third switch arecontrolled in a closed state, and the second switch is controlled in anopened state, and the control unit is configured to record a firstpattern comprising values of the third detection voltage measured aplurality of times according to time during the first switching cycle,and determine a short circuit of the first contactor based on the firstpattern.
 5. The diagnostic apparatus of claim 3, wherein the inactivesection comprises a second switching cycle in which the first switch iscontrolled in an opened state, and the second switch and the thirdswitch are controlled in a closed state, and the control unit isconfigured to record a second pattern comprising values of the thirddetection voltage measured a plurality of times according to time duringthe second switching cycle, and determine a short circuit of the secondcontactor based on the second pattern.
 6. The diagnostic apparatus ofclaim 3, wherein the inactive section comprises: a first switching cyclein which the first switch and the third switch are controlled in aclosed state, and the second switch is controlled in an opened state;and a second switching cycle in which the first switch is controlled inan opened state, and the second switch and the third switch arecontrolled in a closed state, and the control unit is configured todetermine that the first contactor and the second contactor are in anormal state when the third detection voltage is gradually decreasedwhile having a positive value during the first switching cycle, and isgradually increased while having a negative value during the secondswitching cycle.
 7. The diagnostic apparatus of claim 6, wherein thecontrol unit is configured to determine that the first contactor and thesecond contactor are short-circuited due to malfunction when a value ofthe third detection voltage is maintained constant during the firstswitching cycle or the second switching cycle.
 8. The diagnosticapparatus of claim 1, wherein the control unit comprises: amicroprocessor; a multiplexer configured to select at least one of thefirst to third detection voltages, in response to a signal provided fromthe microprocessor; and an analog-digital converter (ADC) configured toconvert a detection voltage selected by the multiplexer to a digitalsignal and transmit the digital signal to the microprocessor.
 9. Thediagnostic apparatus of claim 1, wherein another end of each of thefirst protection capacitor and the second protection capacitor iscommonly connected to the ground.
 10. The diagnostic apparatus of claim1, wherein the control unit is configured to output a first alarm signalnotifying an execution result of the first diagnostic function and asecond alarm signal notifying an execution result of the seconddiagnostic function.
 11. A power system comprising the diagnosticapparatus according to claim
 1. 12. An electric car comprising the powersystem according to claim 11.